1. Field of the Invention
The present invention relates to a substrate processing apparatus for processing a substrate, and a method of manufacturing a semiconductor device which includes a process of processing a substrate by using the substrate processing apparatus, and more particularly, to an oxidation apparatus for oxidizing the surface of a substrate, and a method of manufacturing a semiconductor device, such as IC, which includes a process of oxidizing a substrate by using the oxidation apparatus.
2. Description of the Prior Art
FIG. 1 is an overall view of an apparatus for manufacturing a semiconductor device (semiconductor manufacturing apparatus) as a conventional substrate processing apparatus. The conventional apparatus is configured by a cassette stocker 1′ that mounts a wafer cassette, a boat 3′, a wafer transfer unit (transfer device) that transfers a wafer between the wafer cassette mounted on the cassette stocker 1′ and the boat 3′, a boat elevating unit (boat elevator) 4′ that loads the boat 3′ into a heat-treating furnace and unloads the boat 3′ from the heat-treating furnace, and the heat-treating furnace 5′ provided with a heating unit (heater).
To explain the prior art, the heat-treating furnace 5′ of the semiconductor manufacturing apparatus having the configuration of FIG. 2 is exemplified. The apparatus shown in FIG. 1 includes the boat 3′ that holds about 100 to 150 sheets of stacked wafers 6′, main nozzles 7′, sub-nozzles 8′ arranged in multiple stages, a heater 9′, a reaction tube 10′, and a gas exhaust outlet 11′. A gas supply unit configured by the main nozzles 7′, as shown in FIG. 3, may be configured in a form of a shower plate 12′. This apparatus forms a silicon oxide film as an oxide film on a wafer 6′, such as a silicon wafer, by supplying from the main nozzles 7′ O2 gas at a flow rate of several thousands of sccm and H2 gas at a flow rate lower than O2 gas, for example, several hundreds of sccm, at a temperature of about 850 to 950° C. and under a low pressure environment of about 0.5 Torr (67 Pa) and also by assistantly supplying H2 gas at a relatively low flow rate from the sub-nozzles 8′ at the same time so as to form a film uniformly over the entire stacked wafers.
It is known that the growth of the oxide film requires O2, but the growth rate of the oxide film is extremely low in a source gas of an O2 single body under a low pressure environment of about 50 Pa. Hence, the growth rate of the oxide film gets faster when H2 gas is added (for example, see Patent Document 1). Also, the oxide film is not formed in an H2 single body. That is, when seen as a whole, the growth of the oxide film depends on concentrations (flow rates or partial pressures) of both O2 and H2.